package com.example.demo.test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * @Description 三数之合-排序加双指针
 * @Author wzh
 * @Date 2022/6/10 10:39 上午
 * @Version 1.0
 */
public class Lc15 {
    public static void main(String[] args) {

    }

    public List<List<Integer>> threeSum(int[] nums) {
        List<List<Integer>> ans = new ArrayList<>();
        Arrays.sort(nums);
        int n = nums.length;
        for (int first = 0; first < n; first++) {
            if(first > 0 && nums[first] == nums[first-1]){
                continue;
            }
            int target = - nums[first];
            int third = n - 1;
            for (int second = first+1; second < n; second++) {
                if(second > first+1 && nums[second] == nums[second-1]){
                    continue;
                }
                while (second < third && nums[second]+ nums[third] > target){
                    --third;
                }
                if (second == third) {
                    break;
                }
                if(nums[second] + nums[third] == target){
                    List<Integer> list = new ArrayList<Integer>();
                    list.add(nums[first]);
                    list.add(nums[second]);
                    list.add(nums[third]);
                    ans.add(list);
                }
            }
        }
        return ans;
    }
}
